It really depends upon how much the tomato is eating....

is it a large plant?
Is it growing vegatatively now?
Is it flowering and fruiting now?
What are the climate conditions?

You haven't given enough information to form an opinion.

The plant is about 23" in height and just as wide.
Has about 11 branches. And I believe it's still in it's vegetative state because I only see little green buds coming out at the branch joints. It's indoors sitting on a window sill. It's been raining here for a while now but I think it's been getting good amounts of light. I"m also running my air pump 24/7.

I'll try to post some pics.

-m

It sounds to me like you have your nutrient concentration in line with your plants needs. It is taking up the nutrient and water at the same ratio as you have established.
It is my experience that in hot dry weather when a lot of moisture is being transpired, the EC tends to go up, and in cool weather when little moisture is used, the EC tends to go down. When you have it correct, the EC tends to remain constant.

Norm